Try to start streaming screen capture.

vector/src/main/java/im/vector/app/features/call/VectorCallActivity.kt

@@ -24,6 +24,7 @@ import android.content.Intent
 import android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP
 import android.content.res.Configuration
 import android.graphics.Color
+import android.media.projection.MediaProjection
 import android.media.projection.MediaProjectionManager
 import android.os.Build
 import android.os.Bundle
@@ -32,6 +33,7 @@ import android.util.Rational
 import android.view.MenuItem
 import android.view.View
 import android.view.WindowManager
+import androidx.activity.result.ActivityResult
 import androidx.annotation.StringRes
 import androidx.core.content.ContextCompat
 import androidx.core.content.getSystemService
@@ -76,6 +78,7 @@ import org.matrix.android.sdk.api.session.call.TurnServerResponse
 import org.matrix.android.sdk.api.session.room.model.call.EndCallReason
 import org.webrtc.EglBase
 import org.webrtc.RendererCommon
+import org.webrtc.ScreenCapturerAndroid
 import timber.log.Timber
 import javax.inject.Inject
 
@@ -636,18 +639,36 @@ class VectorCallActivity : VectorBaseActivity<ActivityCallBinding>(), CallContro
 
     private val screenSharingPermissionActivityResultLauncher = registerStartForActivityResult { activityResult ->
         if (activityResult.resultCode == Activity.RESULT_OK) {
-            callViewModel.handle(VectorCallViewActions.StartScreenSharing)
-            // We need to start a foreground service with a sticky notification during screen sharing
             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
-                ContextCompat.startForegroundService(
-                        this,
-                        Intent(this, ScreenCaptureService::class.java)
-                )
-                screenCaptureServiceConnection.bind()
+                // We need to start a foreground service with a sticky notification during screen sharing
+                startScreenSharingService(activityResult)
+            } else {
+                startScreenSharing(activityResult)
             }
         }
     }
 
+    private fun startScreenSharing(activityResult: ActivityResult) {
+        val videoCapturer = ScreenCapturerAndroid(activityResult.data, object : MediaProjection.Callback() {
+            override fun onStop() {
+                Timber.v("User revoked the screen capturing permission")
+            }
+        })
+        callViewModel.handle(VectorCallViewActions.StartScreenSharing(videoCapturer))
+    }
+
+    private fun startScreenSharingService(activityResult: ActivityResult) {
+        ContextCompat.startForegroundService(
+                this,
+                Intent(this, ScreenCaptureService::class.java)
+        )
+        screenCaptureServiceConnection.bind(object : ScreenCaptureServiceConnection.Callback {
+            override fun onServiceConnected() {
+                startScreenSharingService(activityResult)
+            }
+        })
+    }
+
     private fun handleShowScreenSharingPermissionDialog() {
         getSystemService<MediaProjectionManager>()?.let {
             navigator.openScreenSharingPermissionDialog(it.createScreenCaptureIntent(), screenSharingPermissionActivityResultLauncher)

vector/src/main/java/im/vector/app/features/call/VectorCallViewActions.kt

@@ -19,6 +19,7 @@ package im.vector.app.features.call
 import im.vector.app.core.platform.VectorViewModelAction
 import im.vector.app.features.call.audio.CallAudioManager
 import im.vector.app.features.call.transfer.CallTransferResult
+import org.webrtc.VideoCapturer
 
 sealed class VectorCallViewActions : VectorViewModelAction {
     object EndCall : VectorCallViewActions()
@@ -41,5 +42,5 @@ sealed class VectorCallViewActions : VectorViewModelAction {
     data class CallTransferSelectionResult(val callTransferResult: CallTransferResult) : VectorCallViewActions()
     object TransferCall : VectorCallViewActions()
     object ToggleScreenSharing : VectorCallViewActions()
-    object StartScreenSharing : VectorCallViewActions()
+    data class StartScreenSharing(val videoCapturer: VideoCapturer) : VectorCallViewActions()
 }

vector/src/main/java/im/vector/app/features/call/VectorCallViewModel.kt

@@ -348,7 +348,7 @@ class VectorCallViewModel @AssistedInject constructor(
                 handleToggleScreenSharing(state.isSharingScreen)
             }
             is VectorCallViewActions.StartScreenSharing          -> {
-                call?.startSharingScreen()
+                call?.startSharingScreen(action.videoCapturer)
                 setState {
                     copy(isSharingScreen = true)
                 }

vector/src/main/java/im/vector/app/features/call/webrtc/ScreenCaptureServiceConnection.kt

@@ -27,10 +27,17 @@ class ScreenCaptureServiceConnection @Inject constructor(
         private val context: Context
 ) : ServiceConnection {
 
+    interface Callback {
+        fun onServiceConnected()
+    }
+
     private var isBound = false
     private var screenCaptureService: ScreenCaptureService? = null
+    private var callback: Callback? = null
+
+    fun bind(callback: Callback) {
+        this.callback = callback
 
-    fun bind() {
         if (!isBound) {
             Intent(context, ScreenCaptureService::class.java).also { intent ->
                 context.bindService(intent, this, 0)
@@ -45,6 +52,7 @@ class ScreenCaptureServiceConnection @Inject constructor(
     override fun onServiceConnected(className: ComponentName, binder: IBinder) {
         screenCaptureService = (binder as ScreenCaptureService.LocalBinder).getService()
         isBound = true
+        callback?.onServiceConnected()
     }
 
     override fun onServiceDisconnected(className: ComponentName) {

vector/src/main/java/im/vector/app/features/call/webrtc/WebRtcCall.kt

@@ -84,6 +84,7 @@ import org.webrtc.RtpTransceiver
 import org.webrtc.SessionDescription
 import org.webrtc.SurfaceTextureHelper
 import org.webrtc.SurfaceViewRenderer
+import org.webrtc.VideoCapturer
 import org.webrtc.VideoSource
 import org.webrtc.VideoTrack
 import timber.log.Timber
@@ -770,8 +771,27 @@ class WebRtcCall(
         return currentCaptureFormat
     }
 
-    fun startSharingScreen() {
-        // TODO. Will be handled within the next PR.
+    fun startSharingScreen(videoCapturer: VideoCapturer) {
+        val factory = peerConnectionFactoryProvider.get() ?: return
+        val videoSource = factory.createVideoSource(true)
+        val audioSource = factory.createAudioSource(DEFAULT_AUDIO_CONSTRAINTS)
+        val surfaceTextureHelper = SurfaceTextureHelper.create("CaptureThread", rootEglBase!!.eglBaseContext)
+        videoCapturer.initialize(surfaceTextureHelper, context, videoSource.capturerObserver)
+        videoCapturer.startCapture(currentCaptureFormat.width, currentCaptureFormat.height, currentCaptureFormat.fps)
+
+        val videoTrack = factory.createVideoTrack("ARDAMSv0", videoSource).apply { setEnabled(true) }
+        val audioTrack = factory.createAudioTrack("ARDAMSa0", audioSource).apply { setEnabled(true) }
+
+        val localMediaStream = factory.createLocalMediaStream("ARDAMS")
+        peerConnection?.addTrack(videoTrack)
+        peerConnection?.addTrack(audioTrack)
+        localMediaStream.addTrack(videoTrack)
+        localMediaStream.addTrack(audioTrack)
+
+        localAudioSource = audioSource
+        localVideoSource = videoSource
+        localAudioTrack = audioTrack
+        localVideoTrack = videoTrack
     }
 
     fun stopSharingScreen() {